CD79A and Cowden disease: If the serum TG2-IgA and DGP-IgG titers were used to diagnose adult CD without biopsy verification, similar to what has been adapted for children30, then most of the highly TG2-IgA-positive patients (> 70 U/mL, PPV = 0.96) would have been correctly diagnosed with CD (see Supplementary material S3 for more details).